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denoland-deno/extensions/broadcast_channel/in_memory_broadcast_channel.rs
Ben Noordhuis af1546391c feat(extensions): BroadcastChannel WPT conformance
Replaces the file-backed provider by an in-memory one because proper
file locking is a hard problem that detracts from the proof of concept.

Teach the WPT runner how to extract tests from .html files because all
the relevant tests in test_util/wpt/webmessaging/broadcastchannel are
inside basics.html and interface.html.
2021-05-23 15:16:42 +02:00

97 lines
2.5 KiB
Rust

// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
use crate::BroadcastChannel;
use async_trait::async_trait;
use deno_core::error::AnyError;
use std::sync::Arc;
use std::sync::Mutex;
use tokio::sync::broadcast;
use tokio::sync::mpsc;
use uuid::Uuid;
#[derive(Clone)]
pub struct InMemoryBroadcastChannel(Arc<Mutex<broadcast::Sender<Message>>>);
pub struct InMemoryBroadcastChannelResource {
rx: tokio::sync::Mutex<(
broadcast::Receiver<Message>,
mpsc::UnboundedReceiver<()>,
)>,
cancel_tx: mpsc::UnboundedSender<()>,
uuid: Uuid,
}
#[derive(Clone, Debug)]
struct Message {
name: Arc<String>,
data: Arc<Vec<u8>>,
uuid: Uuid,
}
impl Default for InMemoryBroadcastChannel {
fn default() -> Self {
let (tx, _) = broadcast::channel(256);
Self(Arc::new(Mutex::new(tx)))
}
}
#[async_trait]
impl BroadcastChannel for InMemoryBroadcastChannel {
type Resource = InMemoryBroadcastChannelResource;
fn subscribe(&self) -> Result<Self::Resource, AnyError> {
let (cancel_tx, cancel_rx) = mpsc::unbounded_channel();
let broadcast_rx = self.0.lock().unwrap().subscribe();
let rx = tokio::sync::Mutex::new((broadcast_rx, cancel_rx));
let uuid = Uuid::new_v4();
Ok(Self::Resource {
rx,
cancel_tx,
uuid,
})
}
fn unsubscribe(&self, resource: &Self::Resource) -> Result<(), AnyError> {
Ok(resource.cancel_tx.send(())?)
}
async fn send(
&self,
resource: &Self::Resource,
name: String,
data: Vec<u8>,
) -> Result<(), AnyError> {
let name = Arc::new(name);
let data = Arc::new(data);
let uuid = resource.uuid;
self.0.lock().unwrap().send(Message { name, data, uuid })?;
Ok(())
}
async fn recv(
&self,
resource: &Self::Resource,
) -> Result<Option<crate::Message>, AnyError> {
let mut g = resource.rx.lock().await;
let (broadcast_rx, cancel_rx) = &mut *g;
loop {
let result = tokio::select! {
r = broadcast_rx.recv() => r,
_ = cancel_rx.recv() => return Ok(None),
};
use tokio::sync::broadcast::error::RecvError::*;
match result {
Err(Closed) => return Ok(None),
Err(Lagged(_)) => (), // Backlogged, messages dropped.
Ok(message) if message.uuid == resource.uuid => (), // Self-send.
Ok(message) => {
let name = String::clone(&message.name);
let data = Vec::clone(&message.data);
return Ok(Some((name, data)));
}
}
}
}
}
impl deno_core::Resource for InMemoryBroadcastChannelResource {}